Improvement in car-springs



A. MIDDLETON.

CAR-SPRING.

No. 191,361, Patent edMay 29,1877.

WW- M N. PETERS, PHOTD-UTHOGRAPHER, WASNMGTON D O.

UNITED STATES PATENT OFFICE-l.

ALLEN MIDDLETON, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN CAR-SPRINGS.

Specification forming part of Letters Patent No. 191,361, dated May 29,1877 application filed February 27, 1877.

To all whom it may concern:

Be it known that I, ALLEN MIDDLETON, of

Philadelphia, Pennsylvania, have invented a new and useful Improvementin (Jar-Springs, of which the following is a specification:

' My invention relates to improvements in springs composed of steel barscoiled and tempered and the object of my invention is to increase thestrength without any sacrifice of proper resiliency, and to preventfracture.

In the accompanying drawing, Figure 1 is a side view, partly in section,of my improved spring, and Figs. 2 and 3 sections, drawn to an enlargedscale, of the bar of which the spring is composed.

It will be seen that the coiled bar composing the spring is thickest,but lightest, at its outer edge, while the preponderance of metal is ator near the inner edgea rule which must be observed for the followingreasons in carrying out my invention, although the sectional form,

of the bar may be varied. A preponderance of metal at and near the inneredge of the coiled bar, (a feature which of itself I do not claim,)insures the strongest spring, but thelatter is most liable to breakwhere there is the greatest bulk of metal hence the main feature of myinvention, which consists in making the outer edge of the bar thickerthan the inner edge, by forming on the said outer edge a light flange,m, of such a depth that when the coil is compressed, metal to metal, thecontact will be at the flange only, (see Fig.2,) the portions of thecoil composed of the heavy portions of the bar being free from contactwith each other; in other words, the compression of the inner massiveportion of the coil is restricted by the flange at the outer edge of thecoil.

I claim as my invention- A car spring, composed of a coiled bar shapedsubstantially as described-that is, thickest but lightest at the outeredgeand having the preponderance of metal at or near the inner "edge, sothat when the spring is under pressure the contact of the coils witheach other at and near the inner edge shall be prevented by the contactof the coils at the outer edge, all substantially as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ALLEN MIDDLETON.

Witnesses HERMANN MoEssNER, HARRY SMITH.

